This invention relates generally to flow control devices and more particularly to a pressure compensated flow control valve.
Flow control valves have been used for many years in hydraulic systems to regulate quantity of fluid delivered to an actuator or other fluid operated device. Early valves comprised a simple variable orifice which created a given pressure drop across the orifice and for a given inlet pressure accurately controlled the flow rate of fluid to the device. However, any fluctuation in such inlet pressure would cause a variation in flow rate. Thus, to overcome that, a pressure compensator was added to automatically adjust the flow to the variable orifice in response to variations in the pressure drop across the variable orifice. Such a flow control apparatus with precision control is shown in U.S. Pat. No. 3,159,178 to Adams, for example.
Flow control devices of the type above described generally function appropriately. However, one problem encountered is that the variable orifice is normally in an open position. Thus, abrupt initiation of flow at a given pressure will suddenly open the variable orifice and effect a hydraulic shock throughout the hydraulic system.
Recognition of this problem and a solution thereto is shown in U.S. Pat. No. 3,406,714 to Meisel which patent relates to an Anti-Surge Flow Control Valve wherein the pressure compensator is biased to a closed position and then is fully opened upon application of pressure to the valve. However, the valve design as disclosed is extensively complicated and also would be substantially expensive and time consuming to manufacture.